High vacuum, low temperature drying apparatus



Nov. 17, 1942. J. REICHEL EIAL HIGH VACUUM, LOW TEMPERATURE, DRYINGAPPARATUS INVENTORS FER @ORNEY Jomu REICHEL JOSEPH F.. WINK Filed April4, 1941 way altered.

malted Nev. 11,1942

HIGH VACUUM, LO

DRYING John Reichel, Wyn

Winkler,

W TEMPERATURE APPARATUS newood, and Joseph F. Philadelphia, Pa.

Application April 4, 1941, Serial No. 386,878 2 Claims. (01. 3476) Inthe preservation of sera, plasma, proteins or other substances forfuture use, it is necessary that the substances be as completely driedas possible, that this drying be uniform, that the physicalstructure-whether crystalline or amorphous-be not changed and that the.chemical reactions be not interfered with, or, in the event that theproduct is a bacteriological culture or a virus or the like, itseffectiveness be not in any The most recent and advanced method foraccomplishing these objects consists in Dre-freezing the material to bedried and then submitting the frozen mass to a high degree of vacuum inthe presence of regulated heat, whereby the water of the frozen mass isSublimated while the mass is still at a temperature well below thefreezing point.

Our invention therefore relates to a novel selfcontained, portable, highvacuum, low temperature drying apparatus which, we have found in actualpractice, is capable of efilciently and expeditiously carrying out theobjects briefly outlined above, it being understood that, while by wayof illustration we refer to sera, plasma, proteins and similarsubstances, our apparatus is not limited to the drying of thesesubstances only,

but is equally applicable to the drying of other substances aswell.

The full nature of our invention, the structure of our apparatus, themethod Of and the objects which are attained thereby will be moreclearly'understood from the following specification and the accompanyingdrawing in which:

Fig. 1 represents a diagrammatic top plan view of an apparatus embodyingour invention.

Fig. 2 represents a view partly in cross section showing the essentialparts of the invention.

Referring to the drawing in which like reference characters indicatelike parts, and more particularly to Fig. 2, 4 designates a carriage orplatform which is provided with the wheels or rollers 6 and whichconstitutes the sole support of the apparatus thus making the apparatusentirely self contained, portable andeasily movable from one place toanother. On the carriage 4 are suitably supported the compressor 8 andthe condenser Ill which are shown only in outline as they constitutestandard units of conventional low refrigeration equipment. motor whichis secured to the under side of the top of the carriage d as at J4. Themotor I2 is provided with the pulley l6 over which travels the belt l8which also travels over the wheel or pulley 20 to drive the compressor8. 22 desigits operation l2 designates a nates another motor having thepulley 24 over which travels the belt 26 which also engages the wheel orpulley 28 to drive a high vacuum pump which is conventional and hencenot shown in detail. The motor 22 and the vacuum pump are secured to theunder side of the top of the carriage 4 in the same manner as the motorI2 is supported. The bolts or other fastening means of the motor 22 andthe vacuum piunp have been omitted from the drawing for clarity ofillustration. 'If desired, both the compressor 8 and the vacuum pump canbe driven through suitable connections from a, single motor. On thecarriage 4 is also supported by the legs 30 the lower compartment 32,which is preferably bell-shaped, and which is provided with a drainoutlet 34 having the removable air tight plug 36. Within the compartment32 is suitably supported the refrigeration coil 38 which communicatesthrough the pipe 40 which in turn. is enclosed in the outer pipe 42 withthe compressor 8. The compressor 8 communicates with the condensor l0through the conduit 44. The condensor Ill communicates through the pipe46 and the stand pipe 48 with the refrigerating coil 38. The vacuum pumpcommunicates with the interior of the lower compartment 32 through thepipe 52. Seated on the rim of the lower compartment 32 is the workplaten 54 which is of the same shape as the rim of the compartment 32and which extends slightly beyond it as clearly shown in Fig. 2. Thework platform 54 is provided with registering annular recesses in itsupper and lower surfaces for the reception of gaskets of sponge rubberor the like 56. Restingon the upper gasket 56 is the cover 58, which isalso preferably bell-shaped, which is provided with an electric light 60having the socket 62 into which the prongs of an electric plug (notshown) can be inserted, the plug being connected by means of an electricwire to a source of electrical energy. The point at which the electriclight is mounted is made air tight. In the top of the cover 58 is avacuum gauge 64, a thermometer 66 and a vacuum release valve or plug 68.Also mounted in the top of the cover 58 is an electric motor 10 suitablyconnected (by means not shown) to a source of electrical energy andadapted to propel the blade 12. Surrounding the blade 12 and spaced fromthe motor housing is the sleeve 13 which is preferably tapereddownwardly. made of ordinary glass, shatter-proof glass, transparentcomposition, or it may be preferably made of metal such as steel or thelike and, in that event, it is provided with one or more trans- Thecover 58 may be parent windows 14 through which the progress of theoperation may be observed. Extending through the work platform 54 is thepipe I8 the lower end of which exhausts inside the lower compartment 32and the upper end of which is in the form of a funnel F8. on the uppersurface of the work platform 54 are formed a series of depressions orrecesses 80 in each of which is positioned a thin film of mercury orother liquid 82 having a high boiling point. In each of the recesses andresting upon the film of liquid 82 is positioned a container 84 which isin the form of a bottle, an ampule, or the like and which preferably hasan elongated neck somewhat restricted as at 86. Within each of thebottles or other containers 84 is a layer of frozen mass 81 to be dried,the cross sectional thickness of the mass being predetermined accordingto requirements or according to the nature of the material to be driedand also with due regard to the canacity of the apparatus or the degreeof the d ying desired.

The operation is as follows:

The cover 58 is removed from the work platform 54, and bottlescontaining the pre-frozen material are seated in the recesses 80. Thecover 58 is replaced and care is taken to see that the vacuum breakingplug or valve 88 is tight. The refrigerating mechanism comprising thecompressor 8 and the condenser l and their adjuncts are preferablyalready in operation so that the coil 38 is well below the freezingpoint. With the cover 58 in position the vacuum pump is operated so asto draw the highest possible vacuum in the enclosure (formed by thecompartment) 32 and the cover 58 through the pipe 18. Simultaneously,the heating coil 88 carried by the work platform 54 is energized byapplying an electric plug (not shown) leading from a source ofelectrical energy to the socket 98. The vacuum serves to press the cover58 tightly upon its gasket seat 56.

and the greater the vacuum the greater the pressure and hence thetighter and more leak-proof is the seal between the. cover 58 and thework platform 54 and between the work platform 54 and the lowercompartment 32. The handling of the bottles from the centrifuging andfreezing apparatus onto the work platform 54 raises the temperature ofthe bottles up to about minus F. to F. and the heat from the coil 88 isso r controlled as never to raise the temperature of the material 81above a predetermined limit which is considered safe in that it will notinterfere with the chemical reactions, the physical structure of thelife of the material. Such temperature is perhaps about 100 F. Thetemperature thus ap plied tends to melt the frozen water but thecontinuous evaporation under the high vacuum results in constant coolingof the material 81 so that a balance is maintained between the heatdelivered by the coil 88 and the loss of heat due to evaporation. Inthis way the mass of material 81 remains frozen throughout the dryingoperation. The thin film of mercury 82 serves to estab-'- lish perfectcontact between the bottom of the bottles 84 and the work platform 54for even transmission of heat. The function of the motor I8, blowing asit does into the sleeve or funnel 13, is to expeditethe movement of thevapors emanating from the bottles 84 and direct them into the pipe 16thus increasing the vacuum. The

sleeve 13 cooperating with the upper end of the funnel l8 and the blade12 of the motor serves as a jet so that the vapors from the bottles 84travel in substantially the manner illustrated by the arrows in Fig. 2.Since condensation is detrimental to the highest efficiency of thevacuum pump, which under certain circumstances must produce a vacuum aslow as 100 microns or less, it is necessary that only completely drygases be allowed to pass through the vacuum pump and the low temperaturerefrigerating coil 38 serves to condense and freeze the water vaporcontent of the gas drawn through the pipe 16 so that after a period ofoperation the refrigerating coil 38 is frosted or covered with a layerof snow or ice. 92 designates a thermometer which indicates the amountof heat supplied by the coil 88. The thermometer 92 may be a plainthermometer or may be of the thermostatic type whereby automaticregulation may be attained. When the operation is completed the valve 68is opened to break the vacuum to permit removal of the cover 58 andafford access to the bottles 84. When the coil 38 is unduly frosted anelectric plug (not shown) leading to a source of electrical energy isapplied to thesocket 94 so as to energize the coil 96 to melt the ice orfrost deposited on the coil 38. The liquid thus produced is dischargedthrough the drain 34 by removal of the plug 38.

The gauge 64 indicates to the operator the degree of vacuum in theapparatus and the thermometer 86 indicates the temperature. In the eventthat complete sterility is required, apiece of sterile cotton,preferably treated with an eflicient antiseptic, is inserted in the neckof each of the bottles 84 above the restriction 88. This will preventcontamination of the dried material within the bottle when it is exposedto room air during removal from the platform 54 to the point of use orstorage, or while the bottle necks are permanently sealed by fusing orotherwise.

It will be seen that we have devised a compact, efficient, selfcontained and portable unit which is extremely easy to operate and whichpermits of exact control, and by which a relatively large quantity ofmaterial can be dried in each cycle. It will also be seen that in orderto charge the unit with material to be treated, or to remove thematerial after it has been treated, it is merely necessary to remove thecover 58 without disturbing the compartment 32, its adjuncts and theremaining mechanism, that the vacuum drawn in the enclosure of thecompartment 32 and the cover 58 serves automatically to seal the unit,and that to break the vacuum it is merely necessary to turn the plug 88.The detachable electrical connections to the light and the motor 10 makeit possible to remove the cover 58 easily, and, since the light 60, themotor 10, the thermometer 68 and the vacuum breaking plug 68 are allcarried by the cover 58, they are also removed or applied with itwithout the necessity of dismantling. An important feal ture of ourinvention is the provision of the lower fixed compartment 32 and thework platform 54 which serves as a cover for the compartment 32 andwhich also serves as a support and vacuum seal for the cover 58. Also,the heating element 88 carried by the work platform 54 serves to applythe desired heat to a plurality of hottles 84 only one of which is shownfor clarity of illustration.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is.

1. An apparatus of the character stated comprising a compartment havingan upper open rim, a platform seated on the rim of the open end of saidcompartment, there being a pluralfixed compartment, having an open top,also mounted on said carriage, a refrigerating coilin said lowercompartment operatively connected to said refrigerating mechanism, avacuum pumpoperatively connected to said lower compartment, a platformseated on the rim of said lower compartment and adapted to support thematerial to be dried, there being a through opening in said platform, acasing having an open 2. A portable, self contained apparatus of thecharacter stated comprising a carriage, a refrigerating mechanismmounted thereon, a vacuum pump also mounted on said carriage, a lowerbottom and seated on said platform for enclosing said material, andmeans for efiecting air tight engagement between said platform and saidlower compartment and said platform and said casing.

JOHN REICHEL. JOSEPH F. WINKLER.

